> But, 1) I need to manually adjust the location of "10^5" on top of the y
Sorry for butting in, but I thought that that was the idea: that you
can place 10^5 wherever you want to.
If you want to do it automatically, then you just have to call a dummy
plot before your actual plot, and deduce what the yrange is. So,
something like this should work:
set format y "$%.1t$"
plot 'foo' u 1:2 w l
lmax = int(log10(GPVAL_Y_MAX))
expo = 10**lmax
set label sprintf("X 10^%d", lmax) at graph 0, 1.05
plot 'foo' u 1:($2/expo)